In general, when radiation comprising charged particles such as rays or rays passes through matter, the radiation loses energy by ionizing, exciting and dissociating atoms and molecules which exist in the matter. At the same time, the energy thus lost is converted into thermal motion energy, or transformed into electromagnetic energy to be discharged, or used as energy for creating charge carriers. Particularly, when the radiation is the one incident on a semiconductor, a significant part of energy lost from the incident particles is employed as energy for creating a pair (a carrier) of an electron and a hole. With respect to non-charged radiation such as X-rays, γ rays, neutron rays or the like, the same phenomena described above also occurs by an impact of secondary electrons generated in the interaction between the matter and these rays. Then, these carriers such as electrons and holes which have been generated are collected and captured as an electric signal by an electric field and thereby radiation detection is generally performed by a semiconductor.
As semiconductors which generate the carriers along with passage of radiation, there exist inorganic semiconductors represented by silicon, germanium crystal or the like and organic semiconductors represented by polyaniline, polythiophene or the like.
By being produced as ultrapure crystal, the inorganic semiconductor is provided with a reduced dark current and an excellent S/N ratio. Therefore, the inorganic semiconductor is being extensively employed as a real-time sensor in a radiation detector.
On the contrary, the organic semiconductor is low in cost as compared to the inorganic semiconductor and is possessed of excellent properties such as flexibility to be easily bent or the like. The organic semiconductor, however, is presently poor in sensitivity as compared to the inorganic semiconductor due to an impact of its impurities, nonuniformity of polymer molecular mass, etc. thus not yet having come to practical use as a sensor of real-time radiation detection in the existing circumstances.    Patent document 1: Japanese unexamined patent application publication No.: H10-284748    Patent document 2: Japanese unexamined patent application publication No.: H5-3337    Non-patent document 1: “Detectors for Particle Radiation Basis and Application of Radiation Measurement” written by K. Kleinknecht, translated by Kasuke Takahashi and Hajime Yoshiki, published by Baifukan, 1987